Pen, Electric.
A stylus for producing a series of perforations in paper, so that the
paper may act as a stencil for the reproduction of a great number of
copies of the original matter. Various kinds of electric pens have been
invented. One kind, invented by Edison, consists of a handle carrying an
electric motor actuating a needle, which is driven in and out of the
other end of the handle with high rapidity. It is used by being held
vertically on the paper with the needle end downward, and is moved so as
to describe perforated letters or designs. The paper is then used as a
stencil with an ink roller to reproduce the writing or design ad
libitum. A simpler kind dispenses with the motor and depends on the
perforations produced by the electric spark. As shown in the cut the
stylus is one terminal of an induction coil circuit. The support on
which the paper rests is the other terminal and must be a conductor. In
use the induction coil is started, and the stylus is moved over the
paper; a series of sparks pass through the paper from stylus to the
supporting tablet, perforating the paper and producing a stencil to be
used for reproduction.
Fig. 256. ELECTRIC PEN.
Pentane Standard, Harcourt's.
A standard of illuminating power; in it the combustible substance is a
gas made by mixing one cubic foot of air with three cubic inches of
liquid pentane, measured at 60° F. or, if measured as gases, 20 volumes
of air to 7 of pentane. It is burned at the rate of 0.5 cubic foot per
hour from a cylindrical tube one inch in diameter, closed at the top by
a disc 0.5 inch thick with a hole 0.25 inch in diameter, through which
the gas issues. It gives a flame 2.5 inches high.
The pentane used is the distillate of petroleum which boils at 50° C.
(122° F.) ; it has a specific gravity at 15° C. (60° F.) of from 0.628
to 0.631. It is almost pure pentane (C5H12).
As long as the rate of consumption is between 0.48 and 0.52 cubic foot
per hour the flame gives practically the same light.